RegionGeom¶

class gammapy.maps.RegionGeom(region, axes=None, wcs=None)[source]¶

Bases: gammapy.maps.Geom

Map geometry representing a region on the sky.

Parameters

regionSkyRegion: Region object.
axeslist of MapAxis: Non-spatial data axes.
wcsWCS: Optional wcs object to project the region if needed.

Attributes Summary

`as_energy_true`	If the geom contains an energy axis rename it to energy true
`axes`
`binsz`
`center_coord`	(`astropy.coordinates.SkyCoord`)
`center_pix`
`center_skydir`	Center skydir
`data_shape`	Shape of the Numpy data array matching this geometry.
`frame`
`is_allsky`
`is_flat`	Whether the geom non spatial axes have length 1, i.e.
`is_hpx`
`is_image`
`is_regular`
`projection`
`region`
`wcs`
`width`	Width of bounding box of the region

Methods Summary

`bin_volume`()
`contains`(coords)	Check if a given map coordinate is contained in the geometry.
`contains_pix`(pix)	Check if a given pixel coordinate is contained in the geometry.
`coord_to_idx`(coords[, clip])	Convert map coordinates to pixel indices.
`coord_to_pix`(coords)	Convert map coordinates to pixel coordinates.
`copy`(**kwargs)	Copy and overwrite given attributes.
`create`(region, **kwargs)	Create region.
`crop`()	Crop the geometry at the edges.
`downsample`(factor, axis_name)	Downsample the spatial dimension of the geometry by a given factor.
`drop`(axis_name)	Drop an axis from the geom.
`energy_mask`([energy_min, energy_max, …])	Create a mask for a given energy range.
`from_hdulist`(hdulist[, format])	Read region table and convert it to region list.
`get_coord`([frame])	Get map coordinates from the geometry.
`get_idx`()	Get tuple of pixel indices for this geometry.
`pad`()	Pad the geometry at the edges.
`pix_to_coord`(pix)	Convert pixel coordinates to map coordinates.
`pix_to_idx`(pix[, clip])	Convert pixel coordinates to pixel indices.
`resample_axis`(axis)	Resample geom to a new axis binning.
`separation`(position)
`slice_by_idx`(slices)	Create a new geometry by slicing the non-spatial axes.
`solid_angle`()	Solid angle (`Quantity` in `sr`).
`squash`(axis_name)	Squash geom axis.
`to_bands_hdu`([hdu, hdu_skymap, format])
`to_cube`(axes)	Append non-spatial axes to create a higher-dimensional geometry.
`to_image`()	Create 2D image geometry (drop non-spatial dimensions).
`union`(other)	Stack a RegionGeom by making the union
`upsample`(factor, axis_name)	Upsample the spatial dimension of the geometry by a given factor.

Attributes Documentation

as_energy_true¶: If the geom contains an energy axis rename it to energy true

axes¶

binsz = 0.01¶

center_coord¶: (astropy.coordinates.SkyCoord)

center_pix¶

center_skydir¶: Center skydir

data_shape¶: Shape of the Numpy data array matching this geometry.

frame¶

is_allsky = False¶

is_flat¶: Whether the geom non spatial axes have length 1, i.e. if the geom is equivalent to an image.

is_hpx = False¶

is_image = False¶

is_regular = True¶

projection = 'TAN'¶

region¶

wcs¶

width¶: Width of bounding box of the region

Methods Documentation

bin_volume()[source]¶

contains(coords)[source]¶

Check if a given map coordinate is contained in the geometry.

Parameters

coordstuple or MapCoord: Tuple of map coordinates.

Returns

containmentndarray: Bool array.

contains_pix(pix)¶

Check if a given pixel coordinate is contained in the geometry.

Parameters

pixtuple: Tuple of pixel coordinates.

Returns

containmentndarray: Bool array.

coord_to_idx(coords, clip=False)¶

Convert map coordinates to pixel indices.

Parameters

coordstuple or MapCoord: Coordinate values in each dimension of the map. This can either be a tuple of numpy arrays or a MapCoord object. If passed as a tuple then the ordering should be (longitude, latitude, c_0, …, c_N) where c_i is the coordinate vector for axis i.
clipbool: Choose whether to clip indices to the valid range of the geometry. If false then indices for coordinates outside the geometry range will be set -1.

Returns

pixtuple: Tuple of pixel indices in image and band dimensions. Elements set to -1 correspond to coordinates outside the map.

coord_to_pix(coords)[source]¶

Convert map coordinates to pixel coordinates.

Parameters

coordstuple: Coordinate values in each dimension of the map. This can either be a tuple of numpy arrays or a MapCoord object. If passed as a tuple then the ordering should be (longitude, latitude, c_0, …, c_N) where c_i is the coordinate vector for axis i.

Returns

pixtuple: Tuple of pixel coordinates in image and band dimensions.

copy(**kwargs)¶

Copy and overwrite given attributes.

Parameters

**kwargsdict: Keyword arguments to overwrite in the map geometry constructor.

Returns

copyGeom: Copied map geometry.

classmethod create(region, **kwargs)[source]¶

Create region.

Parameters

regionstr or SkyRegion: Region
axeslist of MapAxis: Non spatial axes.

Returns

geomRegionGeom: Region geometry

crop()[source]¶

Crop the geometry at the edges.

Parameters

crop_width{sequence, array_like, int}: Number of values cropped from the edges of each axis.

Returns

geomGeom: Cropped geometry.

downsample(factor, axis_name)[source]¶

Downsample the spatial dimension of the geometry by a given factor.

Parameters

factorint: Downsampling factor.
axis_namestr: Axis to downsample.

Returns

geomGeom: Downsampled geometry.

drop(axis_name)¶

Drop an axis from the geom.

Parameters

axis_namestr: Name of the axis to remove.

Returns

geomGeom: New geom with the axis removed.

energy_mask(energy_min=None, energy_max=None, round_to_edge=False)¶

Create a mask for a given energy range.

The energy bin must be fully contained to be included in the mask.

Parameters

energy_min, energy_maxQuantity: Energy range

Returns

maskndarray: Energy mask

classmethod from_hdulist(hdulist, format='ogip')[source]¶

Read region table and convert it to region list.

Parameters

hdulistHDUList: HDU list
format{“ogip”, “ogip-arf”}: HDU format

Returns

geomRegionGeom: Region map geometry

get_coord(frame=None)[source]¶

Get map coordinates from the geometry.

Returns

coordMapCoord: Map coordinate object.

get_idx()[source]¶

Get tuple of pixel indices for this geometry.

Returns all pixels in the geometry by default. Pixel indices for a single image plane can be accessed by setting idx to the index tuple of a plane.

Parameters

idxtuple, optional: A tuple of indices with one index for each non-spatial dimension. If defined only pixels for the image plane with this index will be returned. If none then all pixels will be returned.
localbool: Flag to return local or global pixel indices. Local indices run from 0 to the number of pixels in a given image plane.
flatbool, optional: Return a flattened array containing only indices for pixels contained in the geometry.

Returns

idxtuple: Tuple of pixel index vectors with one vector for each dimension.

pad()[source]¶

Pad the geometry at the edges.

Parameters

pad_width{sequence, array_like, int}: Number of values padded to the edges of each axis.

Returns

geomGeom: Padded geometry.

pix_to_coord(pix)[source]¶

Convert pixel coordinates to map coordinates.

Parameters

pixtuple: Tuple of pixel coordinates.

Returns

coordstuple: Tuple of map coordinates.

pix_to_idx(pix, clip=False)[source]¶

Convert pixel coordinates to pixel indices.

Returns -1 for pixel coordinates that lie outside of the map.

Parameters

pixtuple: Tuple of pixel coordinates.
clipbool: Choose whether to clip indices to the valid range of the geometry. If false then indices for coordinates outside the geometry range will be set -1.

Returns

idxtuple: Tuple of pixel indices.

resample_axis(axis)¶

Resample geom to a new axis binning.

This method groups the existing bins into a new binning.

Parameters

axisMapAxis: New map axis.

Returns

mapGeom: Geom with resampled axis.

separation(position)[source]¶

slice_by_idx(slices)¶

Create a new geometry by slicing the non-spatial axes.

Parameters

slicesdict: Dict of axes names and integers or slice object pairs. Contains one element for each non-spatial dimension. For integer indexing the corresponding axes is dropped from the map. Axes not specified in the dict are kept unchanged.

Returns

geomGeom: Sliced geometry.

solid_angle()[source]¶: Solid angle (Quantity in sr).

squash(axis_name)¶

Squash geom axis.

Parameters

axis_namestr: Axis to squash.

Returns

geomGeom: Geom with squashed axis.

to_bands_hdu(hdu=None, hdu_skymap=None, format=None)¶

to_cube(axes)[source]¶

Append non-spatial axes to create a higher-dimensional geometry.

This will result in a new geometry with N+M dimensions where N is the number of current dimensions and M is the number of axes in the list.

Parameters

axeslist: Axes that will be appended to this geometry.

Returns

geomGeom: Map geometry.

to_image()[source]¶

Create 2D image geometry (drop non-spatial dimensions).

Returns

geomGeom: Image geometry.

union(other)[source]¶: Stack a RegionGeom by making the union

upsample(factor, axis_name)[source]¶

Upsample the spatial dimension of the geometry by a given factor.

Parameters

factorint: Upsampling factor.
axis_namestr: Axis to upsample.

Returns

geomGeom: Upsampled geometry.